Qunqi A4988 Driver CNC Shield Expansion Board for Arduino V3 Engraver When inserting the A4988 module, must be careful not to insert opposite. Stepper motor wiring as follows: 2A, 2B is a group (red, green), 1A, 1B is a group (blue, yellow), if want to change direction, can be change the position of one group , for example 2A, 2B mutually exchanged. 1 X A4988 CNC Shield Expansion Board